Spoiler
So he found the diary of his brother and he found out his brother hated him. And after that the main character ( I'm sorry I'm bad with names) leaves everything behind literally his friend and his school
The reason his brother killed himself because of the rumours about him he didn't want his parents to hear the rumours. Oh and the reading club blamed everything on him the rumour that he's gay and other things. and why he hated his young brother is he was sick and he was jealous that his brother is healthy( I know childish right). Also the main characters best friend right he follows him everywhere because he wanted to protect him from the reading club.
THIS IS WHAT I FOUND I HOPE IT HELPED YOU

Imma drop this because I saw spoiler and the ending was really shitty ┑( ̄Д  ̄)┍